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CONTROLLING THE CURCULIO, BROWN 

ROT, AND SCAB IN THE PEACH 

BELT OF GEORGIA 



OLIVER I. SNAPP 

Entomologist, Fruit Insect Investigations, United States Bureau of Entomology 

WILLIAM F. TURNER 

Assistant Entomologist, Georgia State Board of Entomology, and 

JOHN W. ROBERTS 

Pathologist, United States Bureau of Plant Industry 




UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT CIRCULAR 216 



Contribution from the Bureau of Entomology 
L. O. HOWARD, Chief 

And the Bureau of Plant Industry 

WILLIAM A. TAYLOR, Chief 

In cooperation with the Georgia State Board of Entomology 



Washington, D. C. 



May, 1922 



WASHINGTON : GOVERNMENT PRINTING OFFICE : 1922 



Moaogrrapjfc 






CONTROLLING THE CURCULIO, 1 BROWN- 
ROT, 2 AND SCAB 3 IN THE PEACH BELT 
OF GEORGIA. 



CONTENTS. 



Page. 
The peach crop of 1921 saved from 

the curculio and brown-rot a 

Growth of the peach industry in 

Georgia 4 

Losses from the curculio and brown- 
rot 4 

Character of curculio injury and its 

relation to brown-rot 6 

Orchard sanitation for curculio con- 
trol 7 

Picking up and destroying " drops "_ 9 

Disking as a control measure 13 

Jarring for the curculio 14 



Page. 

Dusting for the curculio after har- 
vest 15 

Results of spraying and dusting ex- 
periments 16 

Dusting and spraying recommenda- 
tions 24 

Directions for preparing spray ma- 
terials 26 

Success with spraying or dusting de- 
pends on thoroughness 27 

Curculio and brown-rot control meas- 
ures must be made annual orchard 
practices 29 



THE PEACH CROP OF 1921 SAVED FROM THE CURCULIO AND 

BROWN-ROT. 

GEORGIA'S RECORD PEACH CROP of 1921 was remarkably 
free from curculio injury and from brown-rot. During that 
season almost twice as much merchantable fruit was shipped out of 
the State as during the preceding year, and at least $10,000,000 was 
received for the crop. This rescued the peach industry in Georgia 
from partial collapse, as the almost complete failures experienced 
during the two preceding years had placed the peach belt in a very 
serious financial condition. 

The success achieved in controlling the curculio and brown-rot, 
after the very heavy curculio infestation during previous years, which 
left vast numbers of beetles in the orchards to prey upon succeed- 
ing crops, was indeed phenomenal, and was due to the fact that the 
growers carried out a program of control measures recommended by 
the United States Bureau of Entomology, the Georgia State Board of 
Entomology, and the United States Bureau of Plant Industry. Fa- 
vorable weather conditions also played a part in the successful control 
of these pests in 1921. During the two previous seasons rains pre- 

1 Conotrachelus nenuphar Hbst. ; order Coleoptera, family Curculionidae. 

* Sclerotinia cinerea. 

■ Cladosporium carpophilum. 



4 Department Circular 216, U. S. Dept. of Agriculture. 

ceding and during peach harvest were frequent. The object of 
this circular is to present to the peach growers of Georgia and 
the South information concerning the various measures used in 
the successful control of the curculio, in order that they may be 
utilized in the future against the pest. The results of the spraying 
and dusting experiments conducted in the Georgia peach belt during 
the season of 1921 are given, along with the spraying and dusting 
schedules, for future use. 

GROWTH OF THE PEACH INDUSTRY IN GEORGIA. 

The culture of peaches in Georgia has increased very rapidly dur- 
ing the last decade, and the industry is now one of the most important 
in the State, the prosperity and financial welfare of a number of 
counties in middle Georgia being dependent, directly or indirectly, 
on the success of the peach crop. Reports of the Bureau of the Cen- 
sus show that in 1890 there were in Georgia 2,787,546 peach trees of 
bearing age ; by 1900 the number had increased to 7,668,639, and by 
1910 and 3,391,851 in 1920. The acreage devoted to peaches has been 
was not due to a decreased commercial peach acreage, but to the 
abandonment of many home orchards. In 1920, 4,788,718 bushels of 
merchantable peaches were produced in the State from commercial 
orchards, as compared with only 2,555,499 bushels in 1910. 

The acreage of peach trees of nonbearing age in Georgia has in- 
creased over 100 per cent during the last 10 years. According to 
the Census reports there were 1,531,367 such trees in the State in 
1910 and 3,391,851 in 1920. The acreage devoted to peaches has been 
greatly increased since the 1920 census figures were obtained and is 
still being increased. The severe damage to the Georgia cotton crop 
by the boll weevil and the recent exceedingly low price of cotton are 
largely responsible for this increase. Many large plantings of peach 
trees are now under way in sections of the State where peaches have 
never been grown commercially before (fig. 1). 

LOSSES FROM THE CURCULIO AND BROWN-ROT. 

The year 1920 will long be remembered by the Georgia grower as 
the " wormy-peach year." The losses to individual growers were 
tremendous, and an exceedingly low estimate of the damage by the 
curculio to the 1920 Georgia peach crop as a whole is placed at 
$2,000,000. According to the Bureau of Markets and Crop Estimates 
of the United States Department of Agriculture, only 5,663 carloads 
of peaches were shipped from the State in 1920 in contrast with 
10,559 carloads in 1921. Many more peaches were produced in 
Georgia in 1920, but they were rendered unmarketable by the curculio. 
The peach crop of 1919 was also a partial failure, owing to combined 



Control of the Curculio, etc., in Georgia. 



injury by the curculio and brown-rot. The shipments for the season 
of 1919, as reported by the Bureau of Markets and Crop Estimates, 
were 7,236 carloads. 



GEORGIA 




Fig. 1.— Outline map of Georgia showing, in solid black, old peach belt ; in dotted areas, 
sections where new plantings are being made. 

The great abundance of the curculio in Georgia during 1920 can 
be attributed directly to the careless and inefficient control measures 
practiced by the growers during preceding years. The progeny of 
a number of generations of the curculio, not satisfactorily controlled, 



6 Department Circular 216, U. S. Dept. of Agriculture. 

had been multiplying for several years. During these years some 
growers failed to spray, and the careless spraying of others was 
worthless. Very often the entire spraying crew rode on the tank 
(fig. 2) and the team was kept walking from one end of the orchard 
to the other, no stops being made as the trees were passed. In many 
cases the spraying was left entirely in the hands of incompetent labor 
with no supervision. With such careless control measures the severe 
curculio damage during 1919 and 1920 was a natural result. 

CHARACTER OF CURCULIO INJURY AND ITS RELATION TO 

BROWN-ROT. 

The plum curculio injures the peach by puncturing it for feeding 
or egg-laying. The feeding puncture very often scars the fruit, and 




Fig. 2. — The kind of spraying responsible for the severe curculio damage in 1920. 

the larva that hatches from the egg deposited in an egg puncture 
lives within the fruit until it is practically full grown and makes 
the fruit unfit for market. 

The curculio not only damages the peach directly, but the rupture 
of the skin for feeding or oviposition furnishes a place for brown-rot 
to enter ; in fact, a very large percentage of the brown-rot infections 
in the peach belt of Georgia are caused in this way. A heavy cur- 
culio infestation, therefore, facilitates the establishment of brown- 
rot infections. 

A majority of the peaches that are punctured by the curculio soon 
after the fruit sets fall to the ground before the stone begins to 



Control of the Curculio, etc., in Georgia. 7 

harden. After the fruit enters the stone-hardening period, which is 
the rapidly growing period of the fruit, there is little curculio ac- 
tivity and very few larvae develop to maturity. As the fruit enters 
the ripening period, however, which is usually about four weeks 
before harvest, curculio activity is resumed, and the larva? readily 
mature in the fruit. 

ORCHARD SANITATION FOR CURCULIO CONTROL. 

The curculio lives over winter in the adult stage, hibernating in 
grown-up fence or terrace rows in or near the orchard, or in near-by 




Fig. 3. — Burning over woodlands to destroy hibernating curculios. 

woodlands, waste fields, pruning piles, or rubbish. The burning 
over of any woodlands or waste land adjacent to peach orchards, 
therefore, undoubtedly destroys many of the adult beetles. Figures 
3 and 4 show a strip of woodland beside a large commercial peach 
orchard being burned over during the clean-up campaign conducted 
in Georgia during the winter of 1920-21. 

The curculio infestation in the Georgia peach belt in 1920 was 
probably the heaviest that has ever occurred in America. Myriads 
of adult curculios were left to hibernate the following winter. To 
control this vast army of overwintering beetles and save the next 
crop seemed a very difficult problem. It would probably have been 



8 Department Circular 216, U. S. Dept. of Agriculture. 

impossible to combat the insect successfully in Georgia in 1921 with 
spraying and dusting alone, owing to the extremely abnormal cur- 
culio conditions that existed in the State the year before. It was 
necessary to adopt other measures, and the burning and cleaning-up 
campaign waged by the growers during the winter without doubt 
reduced materially the number of curculios that made their appear- 
ance in the spring. 

Not only should the adjoining woodlands and waste lands be 
burned over and the priming, brush, and rubbish heaps be destroyed, 
but the vegetation that has grown up along fence rows should also 




Fig. 4. — Woodlands near peach orchard thoroughly burned over to destroy hibernating 

curculios. 

be grubbed out and destroyed (fig. 5). Terrace rows in and near 
the orchard (fig. 6) should receive some attention during the winter 
months, as both fence and terrace rows grown up to vegetation fur- 
nish excellent hibernating quarters for the curculio. 

There are very few days during the winter months when this 
work can be properly done, as a sweeping, vigorous fire is necessary 
to burn the vegetation and rubbish close to the ground. For this 
work, therefore, orchardists should take advantage of the first dry 
period after the first killing frost in the fall. All undergrowth in 
woods or waste lands within 200 or 300 yards of orchards should be 
burned off, as the burning off of areas of the size thus covered will 



Control of the Curculio, etc., in Georgia. 9 

be sufficient to destroy a majority of the insects hibernating in such 
places. Sufficient supervision and labor should be close at hand dur- 
ing the burning to handle the fire properly, and precaution should be 
taken to keep it from damaging telephone and telegraph poles, fences 
and fence posts, and all buildings. 

It is not advisable to undertake any burning in the orchard, unless 
it is for the destruction of vegetation or rubbish on a terrace row 
or along a fence, in which case the proper steps should be taken to 
keep the fire from damaging any of the trees. 




Fig. 5. — Cleaning up fence rows to destroy curculio hibernating quarters. 

PICKING UP AND DESTROYING "DROPS." 

A majority of the peaches punctured while small fall to the ground 
within a few weeks after the calyces, or " shucks," have been pushed 
off. The larvae, however, remain in them and develop until, having 
reached maturity, they eat their way out of the fruit and enter the 
soil to transform to adults. Life-history studies conducted by Mr. 
E. R. Selkregg during the season of 1921 show two complete genera- 
tions of the curculio in Georgia. The beetles that result from eggs 
deposited in the small peaches lay the eggs for the second generation. 
The " worms " in the Belle of Georgias and Elbertas in Georgia, and 
in some years those in the Hileys, are mostly second-generation 
larvae. 

89787—22 2 



10 Department Circular 216, U. S. Dept. of Agriculture. 

The importance of picking up and destroying all fallen peaches, 
especially those that fall soon after the shedding of the "shucks," 
can therefore be readily seen. The size of the second generation, 
which is so injurious to the desirable late varieties, can be greatly 
reduced by the systematic destruction of fallen peaches throughout 
the season. This measure probably assisted more than any other in 
controlling the curculio in the 1921 Georgia peach crop ; and peach 
growers in the South would be wise to make this practice, especially, 
a part of their annual program of orchard management. 




Fig. 6. — Clean terrace rows reduced hibernating quarters for the curculio. 

tation work in the orchard. 



Note sani- 



From 75 to 90 per cent of the small peaches that fall to the ground 
shortly after the fruit has set contain one or more larvae, or " worms," 
of the curculio. An experiment conducted at the Peach Pest Lab- 
oratory at Fort Valley, Ga., gives some idea of the results that may 
be expected from the picking up and destruction of these small in- 
fested peaches. About 2£ bushels of " drops " were picked up from 
under trees in the vicinity of Fort Valley soon after the pollination 
season. The fruit was kept in wire cylinders and daily observa- 
tions were made as to the number of larvae, or " worms," which, hav- 
ing reached maturity, left the fruit. Within a few weeks after this 
fruit was gathered more than 13,000 larvae of the curculio had eaten 
their way out of the 2£ bushels of " drops " to enter the soil, where 



Control of the Curculio, etc., in Georgia. 



11 



the pupa stage is passed. The adult curculios that ultimately would 
have resulted from those larvae could have heavily infested a 100,000- 
tree orchard by harvest time. 

It is especially important to pick up the smallest " drops," as these 
are nearly always infested. For this reason it is not advisable to 
pay for the work by the basket, as then an effort is made by the 
laborers to secure the large peaches in order to fill the baskets 
quickly, and many small ones are left. It is very seldom that a 
small, hard, leathery, and dried-up " drop " does not contain a larva 




Fig. 7.- 



-It is important to pick up these small, hard, dried-up " drops," as they are the 
ones usually infested with curculio larva?. 



of the curculio (fig. 7). The larger "drops" (fig. 8) are not so 
likely to contain the " worm." 

Probably the best way to destroy these fallen peaches is by bury- 
ing deeply with quicklime. They should be placed at least 24 inches 
below the soil surface. Growers have found a long trench that can 
be extended from time to time useful for the destruction of " drops." 
The " drops " should be covered with the soil after the quicklime 
has been added. It is very necessary to bury " drops " deeply, so 
that any beetles that might possibly emerge can not get out through 
the soil, as might be the case if the trench were shallow. Some 
growers have tried burning the "drops"; but this is not very satis- 



12 Department Circular 216, U. S. Dept. of Agriculture. 

factory, as many peaches on the outside of the pile are not burned, 
and the heat often causes a number of " worms " to crawl out and 
escape. A few growers throw "drop" peaches into a convenient 
body of water. This may answer the purpose if the stream or lake 
is large enough and not too shallow. 

When this control measure was first advocated, some growers op- 
posed it on the ground that the expense involved in picking up the 
peaches would be too great; after it was tried, however, the cost was 
found to be comparatively small. In Georgia during the season of 
1921, when the price of labor was still high, it averaged about 1 cent 




Pig. 8. — The larger " drops " are not so likely to be infested with curculio larvae. 

per tree for each gathering — a very cheap form of insurance, consid- 
ering the results obtained. 

This is probably the surest of all control measures for the curculio, 
since if the fruit has been picked up and destroyed as advised, the 
orchardist may be certain that the development of all curculios from 
the larvae in fallen fruit has been prevented. In the Gulf States, 
where there is a partial second generation of the curculio annually, 
this practice is almost as important as spraying or dusting. It Would 
be wise, therefore, for peach growers in the South to pick up all 
" drops " frequently and systematically making a special effort to get 
the smallest, hard, dried-up fruits, as these are the ones most likely to 
be infested. The picking up and destroying of drops also aids in the 
control of brown-rot, since the fungus causing this disease is able to 



Control of the Curciilio, etc., in Georgia. 13 

live in and fruit upon the old " mummies " which become sources of 
distribution for this destructive disease. 

DISKING AS A CONTROL MEASURE. 

After the larva or " worm " of the curculio has reached maturity 
in the peach, it eats its way out and enters the soil to pass the pupa 
stage, which is the period of transformation from the larva to the 
adult or beetle. The " worm," however, does not pass into the pupa 
stage immediately after entering the soil, but remains in the larva 
stage for a few days until it can prepare a soil cell to protect it dur- 
ing the transformation. Upon the completion of this cell, which is 




Fig. 9. — Using the extension disk for destruction of curculio pupae. 

merely a small cavity in the soil smoothed by the larva, the " worm " 
changes to the pupa, the helpless, inactive stage in the insect's de- 
velopment. Frequent disking during this period with an extension 
disk (fig. 9), so that the soil can be stirred close to the tree trunks, 
destroys or breaks up many of the pupal cells, and since the insect 
is in a helpless state, another cell can not be prepared. The pres- 
sure and heat of the soil then cause the death of many pupae, in 
addition to those killed directly by the disk or by exposure to the 
elements and predacious enemies. 

The time spent in the soil by the curculio during this period of 
transformation averages about one month, and the pupal cells are 
mostly within 3 inches of the soil surface. Diskings for destruction 



14 Department Circular 216, U. S. Dept. of Agriculture. 

of pupae should begin in the South about May 15 and be repeated 
frequently, at intervals of one week if practicable, until the late 
varieties have been harvested, provided the orchard is not sown 
down to peas or other crops in June or July. An effort should be 
made to disk as close to the tree trunks as possible without scarring 
them, as most of the pupal cells occur under the spread of the 
trees. Since pupae in the soil during May and June develop into 
beetles that are responsible for most of the " worms " in late varie- 
ties at harvest time, this is a highly desirable control measure. 




Fig. 10. — Jarring peach trees to catch the adult curculios. 



JARRING FOR THE CURCULIO. 

In sections where the curculio infestation is expected to be heavy 
it would probably be profitable to jar the trees in the spring, espe- 
cially near woodlands or other hibernating places, to collect the beetles. 
(Figs. 10 and 11.) The beetles leave their hibernating quarters just be- 
fore or at the time the trees are in full bloom. At this season of the 
year their number is much greater on the trees near the places where 
they have hibernated, as it takes some time for them to become dis- 
seminated over the whole orchard. When the beetles are disturbed 
they fold their legs and fall to the ground, or " play possum." They 
are less active during the early morning than at any other time, and 
the jarring can best be done before the sun is very high. During 
cloudy days, however, the operation can be conducted at any time of 



Control of the Curculio, etc., in Georgia. 



15 



the day. The jarring frames should be in pairs, each frame 12 by 6 
feet in area, with a notch about 10 by 10 inches in the middle of the 
side of one frame to receive the tree trunk. Light strips should be 
used in their construction, as otherwise the frames will be too heavy 
to handle. A low grade of cotton sheeting can be used for the cover. 
The trees are jarred with a pole well padded on one end. Burlap 
covered with a piece of old automobile tire makes a very good pole 
padding. 

Several dozen trees can be jarred early in the morning before it 
will be necessary to remove the beetles. After the sun is well up, 
the beetles become active and, although they will fall as soon as 




Pig. 11. — Picking curculios off of jarring frames. 

the tree is jarred, some will begin to crawl off immediately. The 
beetles can be easily killed by dropping them into a small bucket of 
kerosene. The frames can be carried by women or children, two 
to each frame. For each pair of frames five persons are required, 
four to carry the two frames and one to jar the trees. Growers will 
find this control measure more profitable at or near the blooming 
season, in sections of the orchard near hibernating places, than at 
other times or elsewhere. 

DUSTING FOR THE CURCULIO AFTER HARVEST. 

From the time the peaches are harvested until the leaves drop in 
the fall, the adult curculios are forced to derive a large part of their 



16 Department Circular 216, U. S. Dept. of Agriculture. 

food from peach foliage. To ascertain if it is possible to poison 
these beetles with arsenate of lead before they go into hibernating 
quarters so as to reduce the number of overwintering adults, after- 
harvest dusting experiments have been conducted for the last three 
years. Each year the results have been encouraging, but the data 
obtained during the season of 1921 were particularly interesting. 
In a period of 22 days, beginning four weeks after the fruit was 
harvested, the number of curculios increased 70 per cent on an un- 
treated block of 500 trees, owing largely to the emergence of adults 
of the second generation. Adjoining the untreated block was a 
block of trees of similar size that had been dusted with 90 per cent 
hydrated lime and 10 per cent arsenate of lead about four weeks 
after fruit harvest. On the treated block there was a decrease of 
13 per cent in the number of adult curculios caught in the same 
period of 22 days. While the decrease was not great, the chief 
benefit from the application of dust was in controlling second- 
generation adults, which were emerging in numbers during the 
time the work was under way, as shown by the increase in the num- 
ber of beetles caught on the untreated block. 

As an added protection to the succeeding peach crop, growers will 
probably find two after-harvest applications of 90 per cent hydrated 
lime and 10 per cent arsenate of lead profitable. Best results have 
been obtained by making one application about four weeks after the 
fruit has been harvested and another about two weeks later. Appli- 
cations made earlier than four weeks after fruit harvest are not so 
effective, since feeding at that time is confined largely to the few 
fruits left on the trees and on the ground. The curculios much pre- 
fer fruit to foliage for food. 

RESULTS OF SPRAYING AND DUSTING EXPERIMENTS. 

To ascertain at what time the insecticide and fungicide are most 
effective against the curculio, brown-rot, and scab, and to continue 
the work of comparing the efficiency of the liquid spray and the dust, 
a very extensive experiment was conducted in the vicinity of Fort 
Valley, Ga., during the season of 1921. Two hundred and thirty- 
six thousand peaches were cut open to obtain the data on results. 
(Fig. 12.) The experiment was duplicated on two varieties, Hiley 
and Elberta, the two most popular varieties in Georgia. The 
Hiley experiments were conducted in the J. H. Baird orchard, and 
the Elberta experiments in the orchard of the Hale Georgia Orchard 
Co. These orchards were 3 or 4 miles apart, which was desirable in 
order to test the various spraying and dusting schedules against the 
pests in two different localities. Both orchards had suffered very 



Control of the Curculio, etc., in Georgia. 



17 



severely during the previous season from the curculio and brown-rot, 
and near them at a number of places were excellent hibernating quar- 
ters for the curculio. 

Approximately 5,000 trees were utilized in the experiment, and 
they were divided into plats of as nearly 200 trees each as practicable, 
so that the various schedules would have equal chances to prove their 
effectiveness. An effort was also made to place all plats an equal dis- 
tance from the hibernating quarters of the curculio. In the center 
of each plat 10 trees were selected and tagged as record trees. The 
fruit from these trees was harvested separately, and each peach was 
cut open, examined, and recorded so that the exact percentages of 




Fig. 12. — Cutting peaches to determine results of spraying and dusting. 

sound fruit and of fruit injured by the curculio, brown-rot, and scab 
could be ascertained. All drops were collected from these record 
trees throughout the season and examined for data on the curculio 
infestation and the presence of brown-rot and scab. The Hiley 
orchard used for this work was on Norfolk sandy-loam soil and the 
Elberta orchard on Orangeburg sandy loam. Most of the trees were 
healthy and had made good growth. The age of all the Hiley trees 
was 12 years. The age of the Elbertas varied from 4 to 10 years and 
this was unfortunate, as the schedules used on the 4-year-old Elbertas 
did not receive a fair test with the schedules used on the older trees. 



18 Department Circular 216, U. S. Dept. of Agriculture. 

Table 1 gives the schedules used on the various plats. The same 
schedules were used on both Hileys and Elbertas, with the exception 
of Plat XIII, which was used only on the Elbertas. 

Table 1. — Outline of peach spraying and dusting experiments, Fort Valley, Ga., 

1921. 



Plat No. 



Applications. 



1. As petals 
fall. 



2. Between 
falling of 

petals and 
calyces. 



3. As shucks , *• Two weeks 
foil after shucks 

lau - have fallen. 



5. About one 

month before 

ripening. 



6. Seven to 
ten days 

before 
ripening. 



I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

XII. 

XIII. 



Spray . 
Spray . 
Spray . 
Spray . 
Spray . 
Spray. 
Spray . 
Spray. 
Dust.. 
Dust.. 
Dust.. 
Check. 
Spray. 



T. P. L.. 



A. L. L. 
A. L.L. 
A. L. L. 
A. L.L. 
T.P. L. 

D." A '..'.'. 



L.L. 
L.L. 



L.L. 

pVl.'. 



A.... 

A. 10. 



A.L.S.B... 
A.L.S.B... 
A.L.S.B... 
A.L.S.B... 
A.L.S.B... 
A.L.S.B... 
T.P.S.B... 
T. P.S.B... 

D. A 

D. A 

D. A. 10 



S.B 

A.L.S.B.. 

S.B 

A.L.S.B.. 

S.B 

S.B , 

T.P.S.B.. 

S.B 

D. A 

D. A 

D. A. 10 



A.L.S.B. 



T.P.S.B. 
D. A. 



A. L.L 



A. L.L. 



A.L.S.B... 



S.B. (Elber- 
tas only.) 



A. L. = Arsenate of lead powder, 1 pound to 50 gallons of spray. 

L. =Lime water from 3 pounds of stone lime per 50 gallons of water. 

S. B. = Self-boiled lime-sulphur mixture, 8-8-50. 

T. P. = Triplumbic arsenate paste, 2 pounds to 50 gallons of water. 

D. A. =Dust arsenate of lead, 5 per cent; sulphur, 80 per cent; lime, 15 per cent. 

D. A. 10= Dust arsenate of lead, 10 per cent; sulphur, 80 per cent; lime, 10 per cent. 

All dust applications were made with large power dusting ma- 
chines, and the liquid was applied with power sprayers developing 
from 250 to 275 pounds pressure. In ascertaining the results at 
harvest, data were obtained on the commercial production of No. 1 
and cull fruit from each plat in addition to the detailed data on 
the fruit from the record trees. These commercial data were ob- 
tained at the packing sheds, the Hileys being graded on a grading 
machine and the Elbertas graded by hand by experienced peach 
packers. 

HILEY VARIETY. 

Tables 2, 3, and 4 give the results in terms of percentages of the 
spraying and dusting experiments conducted on the Hiley variety. 
Table 2 gives the data obtained on the fruit cut open at harvest 
from the record trees in each plat. The last two columns on the 
right in this table give the percentages of No. 1 and cull fruit har- 
vested from the record trees. These commercial data were obtained 
by grading the fruit before it was cut open for examination. Table 3 
gives the percentage of curculio-wormy fruit in both the drops and 
harvested fruit from the record trees of each plat. Table 4 gives 
the percentages of merchantable and cull fruit from all the trees 
in each plat. 



Control of the Curculio, etc., in Georgia. 



19 



Table 2. — Summary of results from peach spraying and dusting experiments, 
Fort Valley, Oa., 1921 ; Hiley variety, harvested fruit. 





Total 
num- 
ber of 

fruits. 


Per cent of total fruit— 


Plat 
No. 


Cur- 
culio- 
wormy. 


Brown- 
rot. 


Scab. 


Cur- 

culio- 

wormy 

only. 


Brown- 
rot 
only. 


Cur- 
culio- 
wormy 

and 
brown- 
rot. 


Brown- 
rot in- 
fection 
at cur- 
culio 
feeding 
punc- 
ture. 


Brown- 
rot In- 
fection 
at cur- 
culio 
egg or 
larval 
punc- 
ture. 


Sound. 


No. 1 

fruit. 


Cull 

fruit. 


I 

II 
III 
IV 
V 
VI 


5,152 
5,704 
3,973 
3,364 
4,687 
4,672 
5,214 
2,529 
3,044 
4,037 
3,370 
3,000 


15.16 
6.89 
23.74 
13.40 
14.13 
14.85 
12.41 
29.02 
11.56 
18.13 
20.47 
40.79 


1.85 
3.18 
4.35 
2.23 
.98 
2.12 
2.50 
6.69 
2.14 
2.92 
4.13 
4.87 
















14.73 
6.31 
21.95 
12.78 
13.68 
14.19 


0.06 
.11 
.05 
.03 
.02 




1.36 

2.49 
2.51 
1.58 
.51 
1.46 
1.75 
3.76 
1.68 
1.98 
2.94 
2.20 


0.43 
.58 

1.79 
.62 
.45 
.66 
.71 

2.65 
.46 
.89 

1.10 

2.50 


83.42 
90.51 
73.70 
84.99 
85.34 
83.69 
85.82 
66.98 
86.76 
79.84 
76.50 
57.16 


80.67 
83.82 
81.00 
84.71 
85.05 
84.91 
77.66 
72.86 
82.35 
87.82 
82.72 
64.38 


19.33 
16.18 
19.00 
15.29 
14.95 
15 09 


VII 

VIII 

IX 


11.68 
26.33 
11.10 
17.24 
19.37 
37.97 


.02 
.24 


0.02 
.04 


22.34 
27.14 
17.65 


X 

XI 
XII 


.05 
.09 
.17 




12.18 
17.28 
35.62 



Table 3. — Percentage of total fruit curculio-wormy, Hiley variety, ooth 

and harvested fruit, peach spraying and dusting experiments, Fort Valley, Ga., 
1921. 





Total 


Total 




Total 


Total 




number 


per cent ; 




number 


percent > 


Plat No. 


of fruits 


curculio- 


Plat No. 


of fruits 


curculio- 1 




ex- 


wormy. 




ex- 


wormy. 




amined. 






amined. 




I 


9,854 


22.76 


VII 


9,691 


18.63 


II 


11,893 


25. 15 


VIII 


6,773 


47.62 


III 


7,863 


24.48 


IX 


6,876 


26.28 


IV 


6,730 


17.04 


X 


8,310 


26.22 


V 


8,561 


13.23 


XI 


7,000 


26.19 


VI 


8,202 


15.19 


XII 


9,893 


54.14 



Table 4. — Commercial results of fruit from all trees in each plat, Hiley variety, 
peach spraying and dusting experiments, Fort Valley, Ga., 1921. 





Per cent 


Per cent 




Per cent 


Per cent 


Plat No. 


No. 1 


cull 


Plat No. 


No. 1 


cull 




fruit. 


fruit. 




fruit. 


fruit. 


I 


85.42 


14.58 


VII 


81.39 


18.61 


II 


86.16 


13.84 


VIII 


74.71 


25.29 


III 


84.82 


15.18 


IX 


84.41 


15.59 


IV 


8S.66 


11.34 


X 


87.92 


12.08 


V 


87.00 


13.00 


XI 


85.63 


14.37 


VI 


86.34 


13.66 


XII 


69.54 


30.46 



There was no scab in the orchard of the Hiley variety, and very 
little brown rot developed, so that no data of value were obtained 
on the control of these diseases in this orchard. The weather was 
dry and unfavorable for the development of fungous diseases during 
the season of development of this variety. 



\ 



20 Department Circular 216, U. S. Dept. of Agriculture. 

Some interesting and valuable information on curculio control was 
obtained in this orchard, however. To ascertain the effect of early 
spraying for the curculio, both " drops " and harvested fruit must 
be examined, as the early applications of arsenate of lead are directed 
especially against curculio injury to the small peaches. It is impor- 
tant to reduce the curculio infestation in small peaches as much as 
possible in order that the second generation may not be large. 

Table 3, which gives the data from examinations of both the 
" drops " and harvested fruit, shows that the percentage of curculio- 
wormy fruit was lowest on Plat V. This plat received three appli- 
cations of lead arsenate before the fruit entered the stone-hardening 
period, the first of which was applied as the shucks were splitting, 
or between the falling of the petals and shucks. Plats VI, IV, and 
VII, which gave, in the order named, the next lowest percentages of 
curculio-wormy fruit, all received the first treatment of arsenate of 
lead between the falling of the petals and shucks. On the block 
receiving no treatment throughout the season, Plat XII, over one- 
half of the " drops " and harvested fruit was wormy, whereas Plat V, 
one of the sprayed plats, had only 13.23 per cent wormy fruit. 
Those who are inclined to doubt the value of spraying should be 
convinced by these figures. 

The value of an application of arsenate of lead about four weeks 
before the fruit is due to ripen, for the control of the second 
generation of the curculio, is shown in Table 2, which contains the 
data on the harvested fruit alone. Plat II received the same treat- 
ment as Plat I, except that arsenate of lead was used in the last ap- 
plication on Plat II and omitted on Plat I. At harvest Plat II gave 
only 6.89 per cent wormy fruit, whereas Plat I had 15.16 per cent 
wormy fruit, or more than twice as much. Likewise, the treatments 
used on Plats III and IV were the same, except that Plat IV received 
arsenate of lead in the treatment about a month before harvest and 
Plat III did not. At harvest Plat IV gave only 13.40 per cent 
curculio-wormy fruit, whereas Plat III had 23.74 per cent wormy, or 
almost twice as much. In Table 2 the value of spraying is again 
shown by 40.79 per cent wormy fruit at harvest on the plat (No. 
XII) which received no treatment as compared with 6.89 per cent 
wormy fruit on Plat II, one of the treated plats. 

From the data in Tables 2 and 3 it would appear that the liquid- 
spray applications controlled the curculio somewhat better than the 
dust applications. No data are available from the work on the Hiley 
variety during the season of 1921 that would indicate which method 
is most effective in controlling brown-rot and scab. It has been 
the consensus of opinion among many who have tested the two meth- 
ods in the past that there is little difference between them in con- 
trolling brown-rot and scab, but that the liquid seems to control the 



Control of the Curculio, etc., in Georgia. 



21 



curculio a little more satisfactorily than the dust. The dusting 
method has its good points, such as quickness of application, etc., 
but it is not the purpose of this bulletin to discuss at length the rela- 
tive efficiency of the two methods. Plat X, treated with a dust 
formula containing 5 per cent arsenate of lead, gave practically as 
good curculio control as Plat XI, a plat dusted at the same times as 
Plat X but with a dust formula containing 10 per cent of arsenate 
of lead. Plat IX, receiving one more application of dust than the 
other dusted plats, the first treatment being given earlier, produced 
less wormy fruit than the other dusted plats. Eesults showing that 
5 per cent arsenate of lead in a dust mixture would give practically 
as good control of the curculio as 10 per cent, in dusting experiments 
conducted by the senior author during previous years, are in accord 
with the findings in 1921 as noted above. 

Table 4 shows that Plat IV, which received both the early and late 
spray applications of arsenate of lead, gave the highest percentage of 
commercial No. 1 fruit. The commercial grading, as before stated, 
was done by the grading machine, and the fruit from some plats 
was not closely graded. Very often fruit containing curculio injury 
was allowed to go through to the packers. 

/ 

ELBERTA VARIETY. 

Tables 5, 6, and 7 give, in percentages, the results of the spraying 
and dusting experiments conducted on the Elberta variety. Table 5 
gives the data on the fruit at harvest from the record trees, Table 6 
gives the percentages of wormy fruit for both " drops " and har- 
vested fruit from the record trees, and Table 7 gives the commercial 
results from each plat as a whole. 



Table 5. 



-Summary of results of peach dusting and spraying experiments, Fort 
Valley, Ga., 1921; Elberta variety, harvested fruit. 





Total 


Per cent of total fruit. 






















Plat 


number 














Curculic-wormy. 


No. 


of 
fruits. 


Curculio- 
wormy. 


Brown- 
rot. 


Scab. 


Curculio- 
wormy 
only. 


Brown- 
rot 
only. 


Scab 
only. 










Brown- 


Brown- 


Scab. 


















rot, scab. 


rot. 


I 


4,997 


41.51 


31.65 


1.32 


29.19 


5.82 


0.46 


0.04 


0.24 


0.54 


II 


4,729 


28.27 


35.93 


3.44 


17.45 


8.50 


1.69 


.02 


.59 


.82 


III 


9,763 


39.59 


32.48 


1.24 


26.84 


7.01 


.47 


.03 


.33 


.38 


IV 


9,083 


29.67 


19.81 


1.78 


22.50 


4.98 


.97 


.01 


.14 


.38 


V 


6,575 


48.75 


18.49 


2.03 


38.92 


3.01 


.73 


.00 


.21 


1.04 


VI 


5,685 


47.44 


20.94 


.62 


37.73 


2.73 


.28 


.02 


.30 


.19 


VII 


5,737 


37.43 


48.68 


1.07 


19.92 


6.99 


.35 


.02 


.26 


.30 


VIII 


6,953 


50.16 


18.34 


.97 


41.51 


3.60 


.33 


.03 


.32 


.43 


IX 


1,838 


53.00 


46.19 


.86 


31.67 


7.35 


.27 


.00 


1.04 


.27 


X 


1,878 


54.95 


55.81 


2.24 


26.62 


7.61 


.69 


.00 


1.33 


.64 


XI 


1,988 


55.23 


35.80 


3.42 


35.97 


4.98 


.86 


.20 


1.41 


1.46 


XII 


4,844 


45.42 


77.81 


45.56 


4.40 


4.67 


9.10 


.49 


.33 


4.71 


XIII 


9,667 


39.56 


12.78 


.55 


33.94 


2.69 


.32 


.02 


.24 


.14 



22 Department Circular 216, U. S. Dept. of Agriculture. 

Table 5. — Summary of results of peach dusting, etc. — Continued. 





Per cent of total fruit. 


Plat 




Brown-rot 


Brown-rot 


Brown-rot 


Brown-rot 








No. 




infection 


infection 


at curculio, 


at curculio 






Cull 

fruit. 




Brown-rot, 
scab. 


at curculio, 


at curculio 


egg,or larval 


feeding 


Sound. 


No. 1 fruit. 




egg,or larval 


feeding 


puncture 


puncture 










puncture. 


puncture. 


with scab. 


with scab. 








I 


0.08 


11.40 


13.87 


0.10 


0.10 


38.16 


61.31 


38.69 


II 


.42 


9.20 


16.71 


.19 


.30 


44.11 


64.94 


35.06 


III 


.12 


11.86 


12.89 


.15 


.09 


39.83 


60.20 


39.80 


IV 


.10 


6.44 


7.82 


.20 


.12 


56.34 


76.08 


23.92 


V 


.09 


8.50 


6.51 


.08 


.09 


40.82 


69.20 


30.80 


VI 


.04 


9.18 


8.58 


.02 


.07 


40.86 


66.33 


33.67 


VII 


.05 


16.68 


24.33 


.25 


.10 


30.75 


47.15 


52.85 


VIII 


.03 


7.81 


6.40 


.06 


.09 


39.39 


68.33 


31.67 


IX 


.05 


19.91 


17.57 


.11 


.16 


21.60 


43.48 


56.52 


X 


.27 


26.04 


19.92 


.32 


.32 


16.24 


39.24 


60.76 


XI 


.05 


15.69 


12.62 


.50 


.35 


25.91 


58.54 


41.46 


XII 


4.42 


22.36 


18.70 


13.13 


13.71 


3.98 


17.88 


82.12 


XIII 


.01 


5.21 


4.55 


.01 


.05 


52.82 


77.23 


22.77 



Trees in Plats I, II, IV, V, VI, VII, VIII, and XII, 8 years old. 
Trees in Plats III and XIII, 10 years old. 
Trees in Plats IX, X, and XI, 4 years old. 

Table 6. — Percentage of total fruit curculio-wormy, Elberta variety, 
" drops " and harvested fruit, peach spraying and dusting experiments, 
Valley, Ga., 1921. 



both 
Fort 



Plat No. 


Total 
number 
of fruits 

ex- 
amined. 


Total 
per cent 
curculio- 
wormy. 


Plat No. 


Total 
number 
of fruits 

ex- 
amined. 


Total 
per cent 
curculio- 
wormy. 


I 

II 

III 

IV 

V 

VI 

VII 


10,828 
10,672 
15,845 
13,902 
11,004 
10, 128 
12,665 


51.14 
49.01 
37.64 
33.04 
44.59 
48.05 
48.85 


VIII 

IX 

X 

XI 

XII 

XIII 


11,871 
3,635 
3,389 
3,247 
12,433 
14,583 


49.81 
56.23 
57.63 
56.23 
62.32 
32.95 



Table 7. — Commercial results of fruit from all trees in each plat, Elberta va- 
riety, peach spraying and dusting experiments, Fort Valley, Ga., 1921. 





Per cent 


Per cent 




Per cent 


Per cent 


Plat No. 


No. 1 


cull 


Plat No. 


No. 1 


cull 




fruit. 


fruit. 




fruit. 


fruit. 


I 


64.26 


35.74 


VIII 


65.00 


35.00 


II 


70.24 


29.76 


IX 


53.45 


46.55 


III 


67.67 


32.33 


X 


48.52 


51.48 


IV 


77.65 


22.35 


XI 


59.67 


40.33 


V 


71.98 


28.02 


XII 


26.09 


73.91 


VI 


68.64 


31.36 


XIII 


77.33 


22.67 


VII 


57.86 


42.14 









All of the spraying and dusting schedules had a very much more 
severe test on the Elbertas than on the Hileys. A strip of woodland 
adjoined the experimental plats along their entire eastern boundary, 
and this woodland had hibernated myriads of curculio beetles during 
the previous winter. Furthermore, brown-rot had been very severe 



Control of the Curculio, etc., in Georgia. 23 

in this orchard in years past, and the overstimulation of the trees by 
nitrogen on strong soil, in addition to the very thick tree centers, was 
particularly conducive to the development of the disease in 1921. 

Frequent rains occurred just before and during the Elberta sea- 
son, and this also assisted in the development of brown-rot, which 
was very severe in the Elberta experimental orchard. Seventy-eight 
per cent of the fruit harvested from the plat receiving no treatments 
throughout the season was infected with brown-rot. The severity 
of the test to which the schedules were put can be realized from the 
amount of sound fruit harvested from the block receiving no treat- 
ments, as shown in Table 5. This plat (XII) produced only 3.98 
per cent of sound fruit during harvest, the remaining 96.02 per cent 
being damaged by curculio, brown-rot, or scab. 

Referring to Table 6, it will be seen again that the plats that re- 
ceived the early applications of arsenate of lead produced less cur- 
culio- wormy " drops " and harvested fruit. Plat XIII, which re- 
ceived the earliest arsenical application of all, gave the lowest per- 
centage of curculio-wormy " drops " and matured fruit. 

The four applications of triplumbic arsenate used on Plat VIII 
did not control the curculio as well as three applications of the stand- 
ard or diplumbic arsenate. Triplumbic arsenate, which is a slow- 
killing poison, was used on Plats VII and VIII to see if a greater 
number of applications would give better curculio control without 
serious arsenical burning of the foliage. 

The value of a late application of arsenate of lead for the control 
of the second generation of the curculio is demonstrated again in the 
work on Elbertas. Table 5, which gives the results of harvested 
fruit, shows that Plat I gave over 13 per cent more curculio-wormy 
fruit than Plat II. Plat II received arsenate of lead in the treatment 
a month before harvest, whereas it was omitted in the last treatment 
on Plat I; otherwise the treatments on the two plats were similar. 
The spray schedules used on Plats III and IV were the same, except 
that Plat IV received the late application of arsenate of lead and 
Plat III did not. Consequently Plat III gave 10 per cent more 
wormy fruit than Plat IV. The value of spraying is clearly demon- 
strated by comparing the data of Plats XII and XIII of Table 5. 
Spraying increased the percentage of harvested sound fruit 49 per 
cent on Plat XIII as compared with Plat XII, which partly joined 
Plat XIII and received no treatment throughout the season. 

In interpreting the results of this work the efficiency of the late 
applications of arsenate of lead can be measured only from tables 
giving results of harvested fruit, as practically all "drops" had 
fallen before this application was made. In securing information on 
the results from early arsenical treatments the tables giving data on 
both " drops " and harvested fruit must be consulted, as the early 



24 Department Circular 216, U. S. Dept. of Agriculture. 

arsenical treatments are applied especially for the control of the 
curculio in " drops." 

The curculio control on all treated Elberta plats can not be called 
excellent, but in interpreting the results one must first consider the 
very severe test to which all treatments were put. 

The two applications of self -boiled lime-sulphur applied two weeks 
after the shedding of the calyces or shucks, and about one month 
before the fruit ripened, gave good control of brown-rot, consider- 
ing the severity of the test. Seventy-eight per cent of the fruit 
harvested from the blocks of Elbertas receiving no treatment 
throughout the season was infected with brown-rot. The fruit in- 
fected with brown-rot harvested from the plats receiving two appli- 
cations of self-boiled lime-sulphur averaged 25 per cent, or there 
was a reduction of 53 per cent of brown-rot infection by the use of 
the two self-boiled lime-sulphur treatments. There was only 13 per 
cent of brown-rot on one of the plats receiving the two fungicide 
applications. 

The two self-boiled lime-sulphur treatments controlled scab re- 
markably well. Forty-six per cent of the fruit harvested from the 
untreated blocks was scabby, whereas less than 2 per cent of the fruit 
from the plats receiving the fungicide was infected with scab. The 
scab on some of the treated plats was negligible, Plats VI and XIII 
having only about one-half of 1 per cent. 

The results from Plats IX, X, and XI, which are the dusted plats, 
can not be used for comparison with the liquid-sprayed plats in meas- 
uring the efficiency of the two methods of pest control, since the trees 
in these three plats were four years younger than the rest and the 
crop was exceedingly light. The number of fruits per tree was very 
much less on these plats, and consequently the curculio injury would 
run much higher as compared with older trees in the same orchard, 
bearing a heavy crop. 

Table 7 shows that Plats IV and XIII gave the highest percentage 
of commercial No. 1 fruit. Plat IV received an early and a late 
application of arsenate of lead. Plat XIII received an extra early 
arsenate-of-lead treatment. Plat XII, the untreated block, produced 
only 26 per cent commercial No. 1 fruit, which is over 50 per cent 
less than the No. 1 fruit produced on Plats IV and XIII. 

DUSTING AND SPRAYING RECOMMENDATIONS. 

Feeding tests show that it usually takes from four to seven days to 
kill the adult curculio with peach leaves sprayed or dusted with arse- 
nate of lead. Since the beetles are on the trees in numbers at the 
blooming season and since observations show considerable feeding 
on the calyces, or " shucks," before the fruit is exposed or before the 



Control of the Curculio, etc., in Georgia. 25 

" shuck " is split, an application of arsenate of lead immediately after 
the falling of the petals would be very desirable for reducing the 
number of beetles to deposit eggs in the fruit after it is exposed. Fur- 
thermore, the results of the spraying and dusting experiments of 1921 
discussed in this circular show conclusively that the curculio was 
much better controlled on all plats that received an early application 
of arsenate of lead. 

Field observations and laboratory studies conducted during the 
past seasons confirm former studies in that there is little curculio 
activity during the stone-hardening period of the peach, which begins 
from three to four weeks after the shucks have fallen and ends about 
a month before the fruit ripens. Applications of arsenate of lead 
during this period are therefore of little value. 

In order to control the second generation of the curculio, an appli- 
cation of arsenate of lead should be made about four weeks before 
the fruit is due to ripen. The results of experiments previously dis- 
cussed show the value of lead arsenate at that time for the control of 
the second generation of curculio larvae. 

SPRAYING SCHEDULE. 

As a result of studies and experiments conducted during the 1921 
season at Fort Valley, Ga., and elsewhere in the South during pre- 
vious years, the following spraying and dusting schedules for peaches 
are recommended for future use in Georgia and the Gulf States for 
the control of the curculio, brown-rot, and scab. 

First application. — Immediately after the petals (pink part of 
flower) have fallen, use 1 pound of powdered arsenate of lead, plus 
lime water from 3 pounds of unslaked lime, to each 50 gallons of 
water. 

Second application. — When calyces, or "shucks," are shedding, 
which is usually about 10 days after the falling of the petals, use the 
same spray as for the first application. 

Third application. — Two weeks after the second application, or 
about four weeks after the petals have been shed, use 1 pound of 
powdered arsenate of lead with each 50 gallons of 8-8-50 self-boiled 
lime-sulphur. 

Fourth application. — About four weeks before each variety is due 
to ripen, use the same spray as recommended for the third application. 

DUSTING SCHEDULE. 

If the grower desires to use dust instead of liquid, the 80 per cent 
sulphur, 5 per cent arsenate of lead, and 15 per cent hydrated lime 
formula is recommended for all applications. Four applications in 
all should be given as follows: First, immediately after the petals 



26 Department Circular 216, U. S. Dept. of Agriculture. 

have fallen ; second, when the calyces, or " shucks," are shedding, or 
about 10 days after the first dusting ; third, two weeks after the second 
application; fourth, about four weeks before each variety is due to 
ripen. 

DIRECTIONS FOR PREPARING SPRAY MATERIALS. 

The 8-8-50 self-boiled lime-sulphur called for in the spraying 
schedule is made as follows : 

Place 8 pounds of unslaked or stone lime in a 50-gallon barrel, and 
pour over it enough water, preferably warm, to start the slaking. As 
the slaking begins, add 8 pounds of sulphur. Add water from time to 







—US 






A jMfe ' r "' 4 .".'. 


w ~ 



Fig. 13. — Articles necessary for preparing self-boiled lime-sulphur. 

ment for water. 



Note handy arrange- 



time to keep the mixture from becoming dry, but be careful not 
to drown the lime, as this will cause the boiling process to stop 
too soon. After the mixture has boiled about five minutes, or when 
the lime has about finished slaking, cool with water, strain into 
the spray tank, and dilute to 50 gallons. Care should be taken to cool 
the mixture by the addition of water before the red streaks begin to 
appear in it to any extent, as the red liquid is likely to be injurious to 
peach foliage. Better results will be obtained by crushing all lumps 
of sulphur and mixing it with a little water before adding it to the 
slaking lime. (Figs. 13 and 14.) 

The formula may be raised to 16-16-100 or 32-32-200. A large 
container should be used, however, in preparing self-boiled lime- 



Control of the Curculio, etc., in Georgia. 



27 



sulphur with these formulas. Stock solutions can, of course, be 
made up, the proportions given being observed. 

The powdered arsenate of lead which is used in the proportion 
of 1 pound to 50 gallons of the spray solution should first be made 
into a thin paste with water before addition to the spray tank. 

Materials for dusting should be very fine and thoroughly mixed. 
A very light diplumbic arsenate, superfine sulphur guaranteed 95 
per cent to pass a 200-mesh sieve, and hydrated lime should be used 
for all dust mixtures. 




Fig. 14. — Preparation of self-boiled lime-sulphur is an easy and simple operation with 

the proper equipment. 



SUCCESS WITH SPRAYING OR DUSTING DEPENDS ON 
THOROUGHNESS. 

To attain successful pest control with either spray or dust, the 
applications must be made at the right time with thoroughness. (Fig. 
15. ) The failure of many peach growers to secure the proper control 
of insects and diseases very often is directly due to careless spraying 
by inexperienced or unsupervised laborers, whose object is to get over 
the greatest number of trees in a given time, with no attention to how 
well the job is done. When spraying, work on each tree should be 
completed by the spray man before he goes to the next. It is best 
to start on the side of the tree opposite the spray outfit and work 
around it until the entire tree is covered. An effort should be made 



28 Department Circular 216, U. S. Dept. of Agriculture. 

to cover all sides of each peach. This system takes the spray outfit 
down every other middle. Very often a portion of the tree is com- 
pletely missed by the spray when only one-half of the trees are 
sprayed from one middle and finished when the outfit comes up the 
next middle. 

It is quite essential, when using dust, to proceed down each tree 
row, dusting the near side of every tree. (Fig. 16.) It is practically 
impossible to obtain satisfactory results if dusting is done only in 
every second or third tree row. It is best to make each dust appli- 
cation from a different side of the tree, but usually the prevailing 
wind makes this impossible. Avoid wasting the material. If the 
wind is blowing in the same direction that the duster is moving, 




Fig. 15.— Thoroughness is the keynote of successful spraying. 

open the discharge pipe before reaching the tree and close it before 
the tree is passed. If the wind is blowing in the opposite direction 
from the way the duster is moving, then a better job of dusting can 
be accomplished by waiting until the outfit is opposite the tree before 
opening the discharge pipe. Always move the discharge pipe in 
one direction, either horizontally or vertically, until the tree is envel- 
oped in the dust. 

As mentioned before, the severe curculio infestation of 1920 in 
Georgia was due very largely to exceedingly careless spraying, with 
no attention as to when the applications were made. The curculio, 
brown-rot, and scab must be controlled at very definite times, and 



Control of the Curculio, etc., in Georgia. 



29 



spraying and dusting at other times will not bring the desired 
results. It is universally conceded by those connected with the 
peach industry in Georgia that the thorough spraying and dusting, 
the applications of which were made at the time when they would be 
most effective, was the potent factor in the successful control of the 
curculio and brown-rot in the 1921 crop. If the water supply is far 
distant from the orchard or if there are not sufficient spray outfits 
to handle the acreage in a few days, much time can be saved by 
hauling the water to the spray outfits in the orchard (fig. 17). If 
this is done, the spray tank can be refilled at any place in the orchard 
when the spray gives out. Where the spraying job is left almost en- 




Fig. 16. — It is necessary to proceed down each tree row, dusting each tree from one side. 

tirely to laborers, as is the case in most sections of the Georgia peach 
belt, proper supervision should be maintained at all times to see that 
the operation is thoroughly performed. The importance of making 
the spray applications to future peach crops at exactly the right 
time, with special attention to thoroughness, can not be too strongly 
emphasized. 

CURCULIO AND BROWN-ROT CONTROL MEASURES MUST BE 
MADE ANNUAL ORCHARD PRACTICES. 

Peach culture has been practiced so long in Georgia and the acre- 
age has grown to be so extensive that the curculio, brown-rot, and 
other peach pests have established themselves in practically all sec- 



30 Department Circular 216, U. S. Dept. of Agriculture. 

tions of the State. In order to save future Georgia peach crops from 
the curculio, as well as from brown-rot and scab, the control meas- 
ures discussed in this circular should be made annual orchard opera- 
tions with every peach grower. Each winter special attention should 
be given to orchard sanitation, the fence and terrace rows cleaned up, 
brush and pruning piles destroyed by burning, and adjoining wood- 
lands and waste lands burned over. Too much emphasis can not be 
placed upon the importance of picking up all dropped peaches from 
shortly after the blooming season until the fruit is harvested. About 
May 15 disking for destruction of curculio pupae should be started, 




Fig. 17. — Hauling water to the spray outfit in the orchard saves time. 

and continued as frequently as possible thereafter until harvest. The 
spraying or dusting schedule as outlined in this circular should above 
all be closely followed at the exact time indicated and with the utmost 
thoroughness. 

If this program of work is put into practice in its entirety with 
care, future peach crops in Georgia can be saved from pests, re- 
gardless of weather conditions. Should growers again become care- 
less with these control measures, another crop failure can be ex- 
pected, as previous serious peach-pest seasons have left the Georgia 
peach belt with many sources of brown-rot infection and countless 
numbers of adult curculios. 



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